Vacuum pump

Abstract

The present invention relates to a vacuum pump, in particular a turbomolecular pump, comprising a housing and at least one pump stage arranged in the housing, which includes a stator and a rotor that rotates about an axis of rotation relative to the stator during operation and interacts with the stator to effectively pump. The stator has at least one stator component with a stator component surface, and a portion or all of the stator component surface is treated by oxidation, and / or the rotor has at least one rotor component with a rotor component surface, and a portion or all of the rotor component surface is treated by oxidation or by coating with a nickel-containing material. The stator component and / or rotor component comprises a metallic material containing at least one metallic element.The treated portion or the treated entirety of the stator component surface comprises an outer layer that includes a compound of the metallic element formed by the oxidation treatment, and / or the treated portion or the treated entirety of the rotor component surface comprises an outer layer that includes a compound of the metallic element formed by the oxidation treatment, or that is formed by the coating with the nickel-containing material and includes nickel.

Description

[0001] The invention relates to a turbomolecular pump, comprising a housing and at least one pump stage arranged in the housing, comprising a stator and a rotor which rotates around an axis of rotation relative to the stator during operation and which interacts with the stator to effectively pump.

[0002] Depending on the type and quantity of gas being pumped, the rotor of a vacuum pump, especially a turbomolecular pump (TMP), heats up during operation. In many vacuum applications, pumping a large volume of gas causes the vacuum pump, particularly a turbomolecular pump, to operate at its thermal limit because the rotor reaches the maximum temperature at which it can reliably withstand continuous stress. This rotor heating can negatively impact its service life and limit the maximum volume of gas that the vacuum pump can handle.

[0003] To operate a turbomolecular pump safely, either the maximum power consumption must currently be limited to prevent thermal overload of the pump, or the rotor temperature is measured by sensors during operation and used as a control variable. Under certain circumstances, the maximum permissible rotor temperature may be reached even before the motor's maximum drive power has been applied.

[0004] In principle, the heat generated can be transferred via thermal radiation from the rotor to the stator and from there outwards to a (possibly cooled) pump housing. However, improving heat dissipation from the rotor to a stator component requires increasing the temperature difference between the surfaces involved. The surface temperature of the stator component must therefore be as much lower as possible than that of the rotor. According to the physical principles of thermal radiation, a body can absorb or emit heat more efficiently the higher the thermal emissivity ε of its surface, i.e., the ratio of its actual radiative power to that of an ideal blackbody radiator.US 2015 / 0354577 A1 discloses a turbomolecular pump in which stator disks made of an aluminum alloy are anodized on those of their outer surfaces opposite the rotor disks, and in which a rotor comprises a nickel-plated cylindrical rotor section and rotor disks which are nickel-plated on their outer surfaces opposite the stator disks.

[0005] The object of the invention is therefore to improve the cooling of a turbomolecular pump in the simplest and most effective way possible, so that a rotor of the pump has a lower rotor temperature under otherwise identical conditions, thereby enabling the turbomolecular pump to be operated safely at both its thermal and performance limits.

[0006] This problem is solved by a turbomolecular pump according to claim 1 or by a turbomolecular pump according to claim 6.

[0007] Such a turbomolecular pump, with a housing and at least one pumping stage arranged in the housing, comprises a stator and a rotor which, during operation, rotates relative to the stator about an axis of rotation and interacts with the stator to effectively pump.

[0008] In a first aspect of the invention according to claim 1, the stator comprises at least one stator component with a stator component surface, and the entirety of the stator component surface is treated by oxidation, and the rotor comprises at least one rotor component with a rotor component surface, and a portion of the rotor component surface or the entirety of the rotor component surface is treated by oxidation, wherein the treated stator component and the treated rotor component comprise a metallic material containing at least one metallic element, wherein the treated entirety of the stator component surface comprises an outer layer comprising a compound of the metallic element formed by the oxidation treatment, and wherein the treated portion of the rotor component surface or the treated entirety of the rotor component surface comprises an outer layer,comprising a compound of the metallic element formed by oxidation treatment, wherein the treated stator component is a Holweck stator of a Holweck pump stage of the turbomolecular pump and / or a stator disk of a turbomolecular pump stage of the turbomolecular pump, and wherein the turbomolecular pump stage comprises spacer rings for the stator disks, and wherein none of the spacer rings has a surface treated by oxidation.

[0009] In a second aspect of the invention according to claim 6, the stator comprises at least one stator component with a stator component surface, and the entirety of the stator component surface is treated by oxidation, and the rotor comprises at least one rotor component with a rotor component surface, and the entirety of the surfaces of all rotor components is completely untreated, i.e., neither treated by oxidation nor coated in any other way, wherein the treated stator component comprises a metallic material containing at least one metallic element, wherein the treated entirety of the stator component surface comprises an outer layer comprising a compound of the metallic element formed by the oxidation treatment, wherein the treated stator component is a Holweck stator of a Holweck pump stage of the turbomolecular pump and / or a stator disk of a turbomolecular pump stage of the turbomolecular pump.and wherein the turbomolecular pump stage comprises spacer rings for the stator disks, and wherein none of the spacer rings has an oxidation-treated surface.

[0010] This means that the compound of the metallic element is a compound of at least one metallic element that is also contained in the metallic material.

[0011] In the present invention, the term "oxidation" is to be understood as not being limited to reactions with oxygen or the formation of oxides, but rather encompassing, in the sense generally accepted in the field of chemistry, all redox reactions in which a metal donates electrons to an oxidizing agent and thereby transitions to a state with a higher oxidation number. For example, a metal can also be oxidized to a metal sulfide. Preferably, however, the oxidation is a reaction of the metallic element that leads to the formation of an oxygen compound, in particular to the formation of an oxide, a hydroxide, and / or an oxide-hydroxide of the metallic element.

[0012] The oxidation treatment can, in particular, be anodic oxidation. This refers to an electrochemical treatment in which the stator or rotor component to be treated is brought into contact with an electrolyte solution and connected to a power source, with the stator or rotor component acting as the anode (positive electrode). Preferably, the oxidation treatment is an anodic oxidation of aluminum or aluminum alloys, also known as "anodizing" or "anodizing process" (electrolytic oxidation of aluminum). Accordingly, the outer layer formed is also called an "anodized layer," and the treated material is also referred to as "anodized."

[0013] Anodizing processes are generally known to those skilled in the art and typically comprise a pretreatment of the metallic material (degreasing, pickling, descaling) to clean and expose the metal surface, the actual anodizing (i.e., anodic oxidation) to convert the aluminum surface into an outer layer of aluminum oxide and / or aluminum hydroxide, and a post-treatment (optional coloring; sealing to close pores). Anodizing is usually carried out with direct current, with the stator or rotor component connected as the anode. The electrolyte solution is typically an aqueous solution of an acid, e.g., sulfuric acid or oxalic acid.

[0014] The process according to the invention is not limited to anodizing or anodic oxidation of stator or rotor components. The stator or rotor component can also undergo other oxidation treatments on its surface, in particular coloring oxidation treatments. Coloring chemical treatments of metals are also referred to as chemical metal coloring. This term describes processes in which a metal or alloy surface reacts chemically with a coloring agent to form a colored metal compound, which can be, in particular, an oxide of the metal. The chemical reaction can be carried out with a coloring solution into which the stator or rotor component is immersed, but can also be a reaction with a gas (e.g., oxygen), a molten salt, or another coloring agent.Surfaces that have undergone machining, particularly subtractive machining, are preferably colored, as they react faster and exhibit a more intense color than other surfaces, such as unmachined, rough, or formed surfaces. Furthermore, this method advantageously allows for a higher emissivity even on contact, mating, or dimensioned surfaces that require machining due to tolerance requirements.

[0015] The coloring chemical treatment can be carried out on a surface of a stator component or rotor component that contains copper, a copper alloy, aluminum, an aluminum alloy, an iron alloy, a magnesium alloy, nickel and / or a nickel alloy as a metallic material.

[0016] Examples of coloring chemical treatments known per se and usable in the present invention are the formation of copper sulfide compounds on the surface of copper or copper alloys, e.g., by treatment with potassium sulfide, ammonium sulfide, or sodium thioantimonate; the formation of copper oxygen compounds on the surface of copper or copper alloys, e.g., by treatment with molten salts of alkali metal nitrites or nitrates, or by treatment with oxidizing solutions of potassium persulfate, potassium permanganate, or potassium chlorate; the formation of iron oxygen compounds on the surface of iron alloys, e.g.,by heating steel in air (so-called "bluing"), by treating steel with molten salts of alkali metal nitrites, nitrates, or dichromates, or by treating it with hot, concentrated sodium hydroxide solutions that also contain oxidizing agents such as sodium nitrate or nitrite (so-called "blackening"); the formation of colored oxygen compounds on the surface of aluminum or aluminum alloys, e.g., by treatment with oxidizing solutions of sodium chromate or potassium permanganate (so-called modified Bauer-Vogel process, MBV); the formation of colored oxygen compounds on the surface of magnesium alloys, e.g., by treatment with oxidizing solutions of sodium dichromate and manganese or copper nitrate; or the formation of sulfur compounds of nickel on the surface of nickel or nickel alloys, e.g., by treatment with sodium thioantimonate.Bluing and blackening are particularly preferred, especially blackening of iron alloys, because this allows a very thin (< 2 µm, preferably ≤ 1 µm and ≥ 0.6 µm), abrasion-resistant oxide layer to be formed without significant change to the dimensions of the component, which is particularly advantageous when coloring contact, fitting or dimension surfaces.

[0017] The above list is merely exemplary, and the coloring treatments usable in the present invention are not limited to the variants mentioned here.

[0018] An outer layer produced by an oxidation treatment differs both from a natural oxide layer on a metallic material and from a coating in the conventional sense.

[0019] On base metals such as aluminum or titanium, an oxide layer spontaneously forms in air, acting as a passivation layer and protecting the underlying metal from further oxidation. However, this natural oxide layer is generally very thin; its thickness is typically on the order of a few nanometers. Therefore, it is neither able to impart a high thermal emissivity to the surface, nor does it exhibit significant porosity that would allow it to incorporate dyes.

[0020] In a conventional coating process, an additional layer of a foreign material is applied to the metallic substrate. The thickness of this additional layer is considerable, which can impair the dimensional accuracy of the coated component. This is particularly undesirable on contact, mating, or dimensioned surfaces within a vacuum pump. For example, this can necessitate a subsequent machining step after coating application to remove the previously applied coating in certain areas. Furthermore, such coatings, lacking a strong bond with the underlying material, can detach over time, leading to a reduction in emissivity and contamination of the pump by detached particles.

[0021] Unlike natural air oxidation or conventional coating processes, oxidation treatment of a metallic material involves a controlled chemical reaction that transforms a portion of the metallic material into one or more metal compounds under controlled conditions. The existing metal surface is thus transformed. This oxidation of the material proceeds from the surface of the workpiece to a depth of several micrometers or several tens of micrometers, depending on the material and the selected process parameters.

[0022] Such a layer, produced by an oxidation treatment, has advantages over both natural oxide layers formed by contact with air and over ordinary coatings.

[0023] The layer produced by oxidation treatment, unlike a natural oxide layer, can significantly increase the thermal emissivity of the surface and, due to its porosity, is able to incorporate dyes.

[0024] Unlike conventional coatings, the oxidized layer's growth into the metal surface means that the layers produced by oxidation treatment only partially extend into the interior of the untreated metal surface. Preferably, an outer layer can extend to a maximum of 50% of its total thickness, while 50% or more of its total thickness, relative to the untreated metal surface, grows into the interior of the metallic material. For example, an outer layer can extend to one-third of its total thickness, while two-thirds of its total thickness, relative to the untreated metal surface, grows into the interior of the metallic material.

[0025] Surprisingly, it was found that it is possible to significantly reduce the rotor temperature in a turbomolecular pump even when all contact, fitting or dimension surfaces of the treated stator components and / or rotor components have been subjected to an oxidation treatment, without subsequently removing parts of the outer layer (e.g., to comply with the required component tolerances or for better fit and heat conduction).

[0026] At the same time, a slight increase in the size of the stator or rotor component due to the oxidation treatment, e.g. by a few micrometers, can even have positive effects at certain points, since, for example, a resulting slight narrowing of a radial Holweck gap can further increase the performance of the turbomolecular pump without jeopardizing the dimensional accuracy.

[0027] Since, as explained above, the dimensions of the stator and rotor components treated according to the invention do not change significantly, it has been found that no adjustments to other parts of the turbomolecular pump are necessary in this respect. The stator and rotor components treated according to the invention can therefore be installed in the same pump housings and assembled with the same pump components as the corresponding untreated stator and rotor components.

[0028] Oxidation treatment can slightly increase the roughness of the treated surface compared to the corresponding untreated surface. For example, the arithmetic mean roughness Ra or the mean roughness depth Rz can each increase by a few micrometers. On an anodized aluminum surface, with typical layer thicknesses of 10 to 20 micrometers, an increase in Ra of up to 2 micrometers relative to the untreated aluminum surface can be observed. This is advantageous because higher surface roughness is usually accompanied by increased thermal emissivity. At the same time, however, a good fit can still be achieved at contact surfaces with other pump components, as only a moderate increase in roughness occurs.

[0029] Unlike a conventional coating, the outer layer formed by oxidation treatment is not a subsequently applied foreign material, but rather an integral part of the workpiece, intimately bonded to the metallic material. This prevents the outer layer from chipping or peeling.

[0030] Finally, an outer layer produced by oxidation treatment also has the advantage of providing effective corrosion protection.

[0031] In unclaimed embodiments, an outer layer of a rotor component can also be formed by coating it with a nickel-containing material. An outer layer formed in this way comprises nickel and also has the advantage of providing effective corrosion protection for the treated surface. Preferably, the nickel-containing outer layer also has a higher thermal emissivity ε at 50°C compared to the untreated surface (e.g., at least 0.3) and thus contributes to improved rotor cooling.

[0032] Coating with a nickel-containing material can, in particular, be nickel plating, and the treated rotor component can thus be a nickel-plated rotor component. This means that the nickel-containing outer layer can contain metallic nickel and can be deposited on the rotor component surface using a conventional electroplating or electroless process. The layer can consist of pure metallic nickel, which, apart from unavoidable impurities, contains essentially no other components. However, it can also contain other metals besides nickel, for example, zinc, and / or nonmetals, in particular phosphorus, oxygen, or sulfur. Specifically, the layer can be deposited electroless ("electroless nickel plating") and / or contain 3 to 14% phosphorus by weight. Optionally, an outer layer containing metallic nickel can be additionally passivated using a standard process.

[0033] The nickel-containing outer layer is preferably a black nickel layer. In addition to nickel, the black nickel layer can also contain zinc and sulfur, particularly in the form of nickel sulfide and zinc sulfide, and exhibit a high thermal emissivity at 50°C (e.g., ε ≥ 0.5). The black nickel layer can be electroplated onto the component using a suitable, commercially available electrolyte solution. Alternatively, the black nickel layer can be applied to a first nickel layer previously deposited on the rotor component. This first nickel layer can be, for example, electroplated nickel or electroless nickel ("electroless nickel," typically with 3 to 14 wt% phosphorus).

[0034] However, the nickel-containing outer layer can also be free of metallic nickel and be formed from nickel compounds, e.g., nickel oxide, and be produced, for example, by physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0035] If a rotor component has an outer layer formed by coating with a nickel-containing material, the thickness of the resulting nickel-containing outer layer is preferably 30 µm or less, more preferably 25 µm or less. The layer thickness is also preferably 15 µm or more, more preferably 20 µm or more. In an unclaimed embodiment, the layer thickness can be 25 µm with a tolerance of ± 3 µm, i.e., the layer thickness in this embodiment can be between 22 µm and 28 µm.

[0036] The resulting outer layer covers substantially the entire surface of the stator component and, in a turbomolecular pump according to the first aspect of the invention, can cover substantially the entire surface of the rotor component. Even if the aim is to achieve the most complete possible coverage of the surface of the stator or rotor component, it may be unavoidable, depending on the oxidation process chosen, that at least a small portion of the surface of the treated stator or rotor component does not undergo oxidation treatment and thus lacks an outer layer. In particular, it is possible that the contact points necessary for carrying out the oxidation treatment (e.g., for establishing the electrical contact in anodic oxidation) are not covered by the outer layer. The same applies to an unclaimed coating of a rotor component with a nickel-containing material.Therefore, when the present invention refers to the "entire" surface or the "totality" of the surface, this also includes a portion of the surface which, while essentially comprising the entire surface of the stator or rotor component, is less than 100% for technical reasons. The treated portion of the surface of the stator or rotor component may, for example, be 90% or more, 95% or more, or 99% or more, based on the total surface of the respective stator or rotor component.

[0037] If treatment of as much of the surface as possible is desired, but is not possible for technical reasons on a portion of the surface (e.g. because contact points must be provided for anodic oxidation), then it is preferred to provide the untreated portions without an outer layer on a part of the surface that is not involved in heat dissipation by radiation, for example on the radially outer surfaces of radially outer Holweck stators facing the housing or the radially outer ends of stator disks facing the housing.

[0038] When the present invention refers to a "treated stator component," it means a stator component in which a portion or all of the surface has been treated by oxidation. Conversely, in the present invention, an "untreated stator component" means a stator component whose surface has not been treated by oxidation. The terms "treated surface" and "untreated surface" used below should be understood accordingly.

[0039] When the present invention refers to a "treated rotor component," it means a rotor component in which a portion or all of the surface has been treated by oxidation. Coating with a nickel-containing material is not claimed. Conversely, in the present invention, an "untreated rotor component" means a rotor component whose surface has not been treated by oxidation and has not been coated with a nickel-containing material. The terms "treated surface" and "untreated surface" used below are to be understood accordingly.

[0040] A turbomolecular pump according to the first aspect of the invention thus comprises a combination of at least one treated stator component and at least one treated rotor component, and a turbomolecular pump according to the second aspect of the invention comprises at least one treated stator component. According to the invention, the treatment of a stator component and the treatment of a rotor component is always by oxidation, while the treatment of a rotor component by coating with a nickel-containing material is not claimed. The turbomolecular pump according to the invention comprises at least one treated stator component.

[0041] The treated surface of the stator or rotor component preferably has a thermal emissivity ε of at least 0.3, more preferably at least 0.4, even more preferably at least 0.5, particularly preferably at least 0.6, very preferably at least 0.7, even more preferably at least 0.8, and most preferably at least 0.9 at 50°C. A high emissivity at 50°C is advantageous because this temperature is within the range of the rotor's usual operating temperature. This ensures particularly effective heat dissipation during operation. The thermal emissivity ε is the total emissivity over the infrared wavelength range from 0.78 µm to 1 mm.

[0042] The thermal emissivity ε of a heated object can be measured using a thermocouple and an infrared thermometer with adjustable emissivity. First, the actual surface temperature at a specific point on the heated object is determined using the thermocouple. Then, the surface temperature is measured with the infrared thermometer, initially set to an emissivity of 1. The emissivity setting on the infrared thermometer is then varied until the temperatures read by the thermocouple and the infrared thermometer match. This allows the actual thermal emissivity of a given heated object to be determined experimentally.

[0043] According to the invention, the entire surface of the at least one stator component is treated. This simplifies the manufacturing of the stator component, as it is not necessary to ensure that only certain parts of the surface are subjected to oxidation treatment and others are excluded.

[0044] However, in a turbomolecular pump according to the first aspect of the invention, it can be advantageous if not the entire surface, but only a portion of the surface of the at least one rotor component is treated, particularly if the rotor is not a single piece but rather a multi-piece design. For example, if the rotor component treated according to the invention is a rotor disk to be attached to a rotor shaft for a multi-piece rotor, it is preferred not to treat the inner diameter of the rotor disk and thus not to provide an outer layer. Alternatively, an outer layer initially formed on the inner diameter can be removed again by local post-processing. This offers the advantage of a better fit of the rotor disk to the rotor shaft. Furthermore, an increased emissivity is not required at this point, since the inner diameter does not contribute to heat dissipation by radiation.

[0045] If the rotor is not made of one piece but of multiple pieces, it can also be advantageous if the rotor shaft is untreated.

[0046] In a one-piece rotor, the rotor shaft and rotor disks are manufactured from a single piece. This can be the case, for example, when a turbomolecular pump does not have a hollow section.

[0047] A one-piece rotor, particularly in magnetically levitated turbomolecular pumps, can have a bell-shaped rotor assembly to house the magnetic bearing and, optionally, a drive motor for the rotor assembly within a cavity inside the bell-shaped rotor assembly. The bell-shaped rotor body can have an interior whose cross-section increases axially perpendicular to the axis of rotation, starting from a high-vacuum side of the rotor assembly. Since the cross-section of the interior of such a bell-shaped rotor body increases axially, the outer circumference of the rotor body also increases in the same direction. Due to the bell-shaped design of the rotor body, such a rotor assembly is also called a bell rotor. On the outside of the rotor body, the bell rotor typically includes several pump stages, which comprise rotor disks as the pumping elements.The rotor disks, together with their respective stator disks (which are not part of the bell rotor), form a pump stage of the turbomolecular pump for which the bell rotor is intended. Between the rotor disks of the bell rotor, there is a space in which a stator disk is located after the bell rotor is installed in the turbomolecular pump. However, a one-piece rotor is not necessarily designed as a bell rotor within the scope of the present invention.

[0048] If the rotor is constructed as a single piece rather than in multiple sections (for example, but not necessarily, as a bell-shaped rotor), then in a turbomolecular pump according to the first aspect of the invention, the entire surface of the rotor can be treated. This simplifies the manufacture of the rotor, as it is not necessary to ensure that only certain parts of the surface are treated and others are excluded.

[0049] However, within the scope of the present invention, it is also possible, if necessary, to locally remove an outer layer formed by an oxidation treatment, for example by machining processes. For example, it may be advantageous to first treat a one-piece rotor over its entire surface and then to completely or partially remove the outer layer formed thereby, at least on selected contact, mating, or dimensioned surfaces, such as a ball bearing seat, by post-processing.

[0050] However, outer layers formed by the oxidation of a metallic material largely grow into the surface of the metallic material relative to the untreated surface, and only partially contribute to its thickness. This means that dimensional accuracy relative to other components in the assembled state of the turbomolecular pump can be ensured even if the entire surface of the stator component or rotor is treated, even if no subsequent removal of the outer layer takes place at any point on the surface (e.g., on stator disks), or if subsequent removal of the outer layer only takes place on some of the contact, mating, or dimension surfaces (e.g., on a ball bearing seat of a one-piece rotor).The fact that such post-processing can only take place in certain areas or be omitted entirely, and yet the required component tolerances can still be met even on contact, fitting or dimension surfaces, results in the advantage of a simplified manufacturing process for the stator component or the rotor.

[0051] Surprisingly, it has turned out that effective rotor cooling can also be achieved with stator components whose entire surface is treated and from whose contact, fitting or dimension surfaces no material is removed after the oxidation treatment, as is otherwise usual, for example, to achieve a better fit and heat conduction at contact surfaces.

[0052] The treated portion or the entire treated surface may exhibit a coloration. This coloration can arise because the metallic compound itself is colored, or because a dye—that is, a colored substance distinct from the metallic compound—is contained in the outer layer. It is also possible to combine these methods for generating the coloration, for example, by providing an outer layer with a colored metallic compound that additionally contains a dye.

[0053] Outer layers produced by oxidation treatment, particularly anodic oxidation, of a metallic material, such as anodized layers on aluminum-based materials, exhibit a certain degree of porosity. This is advantageous because the resulting adsorption capacity can be used to introduce one or more dyes into the pores of the metal compound layer. The resulting coloration of the outer layer can, for example, be blackening. This is typically achieved by first immersing the component in a dye solution after the application of the outer layer through oxidation treatment (e.g., anodic oxidation) to enable adsorption of dye particles into the pores, and then subjecting the component to a densification treatment that seals the pores. This densification can be achieved by treatment with boiling water.Dyes suitable for such coloring, especially blackening, can be either inorganic or organic. They are generally known to those skilled in the art and commercially available.

[0054] Suitable organic dyes include anionic anthraquinone dyes and azo dyes. Inorganic dyes can be colored metal compounds, with metals such as chromium, copper, iron, nickel, and cobalt being among the options. Examples include blue iron hexacyanoferrate and black cobalt sulfide. Water-soluble compounds or complexes of the metals, such as iron(III) ammonium oxalate solution, can be used to prepare the dipping bath for dyeing. The dyeing process can also be carried out in two stages, for example, by first dipping the anodically oxidized object to be dyed into a cobalt(II) acetate solution and then into an ammonium sulfide solution, which leads to the formation of black cobalt(II) sulfide in the pores.

[0055] Coloring can enhance the desired effect of rotor cooling, as the coloring, especially blackening, of the outer layer can lead to a further increase in thermal emissivity compared to a stator component with a colorless, uncolored outer layer. Another advantage of a colored outer layer is that such a stator or rotor component is visually distinguishable from other, especially untreated, stator or rotor components.

[0056] A stator component surface treated by oxidation can be further post-treated with a polymer, wherein the polymer is preferably fluorinated, and particularly preferably perfluorinated. The perfluorinated polymer can be derived from a perfluoroolefin monomer. An example of a suitable perfluorinated polymer is polytetrafluoroethylene (PTFE, Teflon).

[0057] The stator component under consideration is a Holweck stator of a Holweck pump stage of the turbomolecular pump and / or a stator disk of a turbomolecular pump stage of the turbomolecular pump.

[0058] It is understood that a treated surface of a Holweck stator receives in particular the thermal radiation emanating from the Holweck rotor opposite it, and thus, due to its improved thermal emissivity (compared to an untreated surface of a Holweck stator made of the same metallic material), results in increased heat dissipation, especially across the radial Holweck gap, and thereby enables a lower operating temperature of the rotor.

[0059] It is also understood that a treated surface of a stator disk in a turbomolecular pump stage receives in particular the thermal radiation emanating from the rotor disks opposite it, and thus, due to its improved thermal emissivity (compared to an untreated surface of a stator disk made of the same metallic material), results in increased heat dissipation, especially across the respective axial gap, and thereby enables a lower operating temperature of the rotor.

[0060] The stator component under consideration can also be a dome located within the Holweck stages, covering the motor and shielding it from the pump system. The dome forms a wall surrounding the motor compartment. That is, the dome can be a wall 221, as found in Fig. 3As shown, a treated surface of such a wall receives, in particular, the thermal radiation emanating from the Holweck rotor opposite it, and thus, due to its improved thermal emissivity (compared to an untreated surface of a wall made of the same metallic material), results in increased heat dissipation, especially across the respective radial gap, and thereby enables a lower operating temperature of the rotor.

[0061] The treated rotor and / or stator component can also be a labyrinth seal, which is typically located above the motor and, due to its (barrier gas) labyrinth, has a particularly large surface area for absorbing radiant heat. It is understood that a treated stator-side surface of such a labyrinth receives, in particular, the thermal radiation emanating from the opposite rotor hub. Therefore, due to its improved thermal emissivity (compared to an untreated surface of a labyrinth made of the same metallic material), it results in enhanced heat dissipation across the respective axial and radial gaps, thus enabling a lower operating temperature of the rotor.Alternatively or additionally, to enhance heat dissipation in the area of ​​the labyrinth seal, it may be advantageous if the rotor-side surface of the labyrinth is treated according to the invention.

[0062] The turbomolecular pump stage of the turbomolecular pump can have multiple stator disks, with several or all stator disks of the turbomolecular pump stage being treated. This is advantageous because it allows the largest possible amount of heat to be dissipated by radiation in the turbomolecular pump stage.

[0063] The Holweck pump stage of the turbomolecular pump can comprise a radially outer Holweck stator and one or more radially inner Holweck stators, wherein either all Holweck stators are treated or only the radially outer Holweck stator is treated. In the present invention, the term "radially outer" Holweck stator is understood to mean the Holweck stator that is located furthest outwards in the radial direction of the turbomolecular pump. Similarly, "radially inner" Holweck stators are understood to mean all Holweck stators that are located further inwards in the radial direction of the turbomolecular pump than the radially outer Holweck stator.

[0064] If all Holweck stators are treated, the advantage is a particularly effective heat dissipation in the Holweck pump stage and thus a particularly effective rotor cooling.

[0065] However, it can also be advantageous if only the radially outer hollow stator is treated, while the radially inner hollow stator, or all radially inner hollow stators, remain untreated. Even tighter tolerances must be maintained along a radially inner hollow stator than along a radially outer one. Although outer layers formed by oxidation treatment of the metallic material largely grow into the surface and only partially contribute to the overall thickness, foregoing treatment can still be advantageous for radially inner hollow stators. This is because the resulting absence of an outer layer makes it easier to ensure dimensional accuracy relative to adjacent components and reliable pump operation.

[0066] Preferably, the turbomolecular pump can comprise at least one turbomolecular pumping stage with a plurality of stator disks and at least one Holweck pumping stage with a radially outer Holweck stator and one or more radially inner Holweck stators, wherein in the turbomolecular pumping stage or each stage, a plurality of, in particular all, stator disks are treated, and in the Holweck pumping stage or each Holweck stator stage, either all Holweck stators are treated or only the radially outer Holweck stator is treated. Because the surfaces of a plurality of, in particular all, stator disks and at least one Holweck stator simultaneously exhibit an increased emissivity, this embodiment allows for particularly effective and uniform heat dissipation and rotor cooling.

[0067] In another embodiment, the turbomolecular pump can comprise at least one turbomolecular pumping stage with a plurality of stator disks and at least one Holweck pumping stage with a radially outer Holweck stator and one or more radially inner Holweck stators, wherein the stator disks of the or each turbomolecular pumping stage are untreated, and in the or each Holweck pumping stage only the radially outer Holweck stator is treated.

[0068] In a further embodiment, the turbomolecular pump can comprise at least one turbomolecular pumping stage with a plurality of stator disks and at least one Holweck pumping stage with a radially outer Holweck stator and one or more radially inner Holweck stators, wherein in the turbomolecular pumping stage a plurality of, in particular all, stator disks are treated and in the Holweck pumping stage all Holweck stators are untreated.

[0069] In a further embodiment, the turbomolecular pump can comprise at least one turbomolecular pumping stage with a plurality of stator disks, wherein in the or each turbomolecular pumping stage a plurality of, in particular all, stator disks are treated and wherein the turbomolecular pump does not have any Holweck pumping stages.

[0070] The turbomolecular pump comprises a turbomolecular pumping stage with spacer rings for the stator disks, none of which have an oxidation-treated surface. Surprisingly, when the turbomolecular pump contains one or more treated stator disks and / or at least one treated Holweck stator, but only untreated spacer rings, a lower rotor temperature is achieved than under the same conditions in an otherwise identical turbomolecular pump with treated spacer rings.To achieve optimal heat dissipation and rotor cooling, it is therefore particularly preferred if a plurality of, in particular all, stator disks are treated in the turbomolecular pumping stage, none of the spacer rings are treated in the turbomolecular pumping stage, and at least one Holweck stator is treated in the Holweck pumping stage, in particular wherein either the radially outer Holweck stator is treated or all Holweck stators are treated.

[0071] The terms "spacer ring" and "spacer ring" are to be considered synonymous in the present invention.

[0072] It is also possible to treat at least part of the surface of the turbomolecular pump housing by oxidation. However, it is preferable to leave the entire surface of the housing untreated.

[0073] According to the invention, the turbomolecular pump comprises at least one stator component treated by oxidation, wherein the rotor, which interacts with the stator in a pumping action, has a surface that is completely untreated, i.e., neither treated by oxidation nor coated in any other way, and wherein the entire surface of all rotor components is untreated. In other words, this means that in a turbomolecular pump according to the second aspect of the invention, no rotating part of the turbomolecular pump is treated, so that only untreated rotating components are provided.

[0074] In a turbomolecular pump according to the first aspect of the invention, the rotor, which interacts with the stator to effectively pump, has a fully or partially treated surface, wherein, in particular, at least one rotor disk is treated. However, in the case of a multi-section rotor, the rotor shaft, as well as, optionally, the Holweck hub (if present) and the Holweck rotor (if present), preferably remain untreated. Furthermore, a rotor with treated rotor components can also be used in a turbomolecular pump that is designed without a Holweck stage, whereby, in this case as well, the rotor shaft preferably remains untreated if the rotor is designed in multiple sections.

[0075] In the present invention, a "treated" surface of a rotor or rotor component is understood to mean a surface that has undergone oxidation treatment in the manner described above for stator components. Turbomolecular pumps with rotor components coated with a nickel-containing layer are not claimed. The surface material of the rotor component is preferably aluminum, an aluminum alloy, titanium, or a titanium alloy.

[0076] In the present invention, an oxidation-treated rotor component surface is in particular a surface treated by anodic oxidation ("anodizing"). Preferably, the oxidation-treated rotor component surface is additionally post-treated with a polymer, wherein the polymer is particularly preferably fluorinated, and most preferably perfluorinated. The perfluorinated polymer can be derived from a perfluoroolefin monomer. An example of a suitable perfluorinated polymer is polytetrafluoroethylene (PTFE, Teflon).

[0077] In a preferred embodiment of the turbomolecular pump according to the first aspect of the invention, the treated rotor component is a rotor disk made of aluminum, an aluminum alloy, titanium or a titanium alloy, which has a surface treated by anodic oxidation on which an oxide layer is formed containing aluminum oxide or titanium oxide, wherein the oxide layer is additionally post-treated with a perfluorinated polymer.

[0078] The turbomolecular pump according to the invention can include rotor disks and / or stator disks designed to be optically sealed in the axial direction. Preferably, however, viewed from the high-vacuum side, at least the first rotor disk and / or the first stator disk is not optically sealed. It can also be advantageous if, in addition, the second rotor disk and / or second stator disk is not optically sealed. It can also be advantageous to design the first three rotor disks and / or the first three stator disks not optically sealed. Within the scope of the present invention, the term "optically sealed" means...

[0079] The invention is understood to mean that, when viewed in the axial direction, there is no direct line of sight between the two sides of the rotor disk or the stator disk. This design has the advantage that backflow losses within the pump can be minimized. The optical tightness can be adjusted, for example, by the degree of overlap between the individual blades. If the disk is optically tight, there is no gap between the blades when viewed axially.

[0080] Discs of a turbomolecular pump stage visible from the high-vacuum side, i.e., rotor discs and / or stator discs of a turbomolecular pump stage, which are visible when viewed from the high-vacuum side, can remain at least partially untreated. The viewing direction from the high-vacuum side can be an axial viewing direction. However, it is not limited to this and can also include viewing angles deviating from the axial viewing direction by more than 0° and less than 90°. Discs visible from the high-vacuum side can therefore also be understood to be discs that, viewed from the high-vacuum side, are still visible at any viewing angle and at any rotor position, which can also include discs that would not be visible in an axial viewing direction from the high-vacuum side.

[0081] For example, disks visible on the high-vacuum side can remain untreated across their entire surface, including the sides of the disks facing away from the high-vacuum side in the axial direction and not visible from there. For example, it is possible to leave the first and / or second rotor disk visible on the high-vacuum side untreated, and alternatively or additionally, it is possible to leave the first and / or second stator disk visible on the high-vacuum side untreated. Likewise, it is possible to leave all stator disks and / or all rotor disks visible on the high-vacuum side untreated. Preferably, at least one rotor disk and / or at least one stator disk visible on the high-vacuum side is treated, but in particular, the treated rotor disk and / or stator disk visible on the high-vacuum side is not the first rotor disk or stator disk, respectively, as viewed from the high-vacuum side.The first stator disk is treated. For example, in a preferred embodiment, the first stator disk and / or the first rotor disk may be untreated, while the second stator disk and / or second rotor disk, which may also be visible from the high-vacuum side, is treated. In such an embodiment, all stator disks or rotor disks following the first treated stator disk or rotor disk (viewed from the high-vacuum side), i.e., the third, fourth, etc., may also be treated.

[0082] The rotor disks and / or stator disks of a turbomolecular pump stage, visible on the high-vacuum side, can also be treated only on a portion of their surface. For example, it is possible to treat the surfaces of these disks only on the sides facing away from the high-vacuum side in the axial direction. However, it is also possible to treat the entire surface of stator disks visible on the high-vacuum side, including the sides of the stator disks that face the high-vacuum side in the axial direction and are visible from there. Similarly, it is possible to treat the surfaces of rotor disks visible on the high-vacuum side, including the sides of the rotor disks that face the high-vacuum side in the axial direction and are visible from there. However, in the case of multi-section rotors, it is preferable for better fit on the rotor shaft if the inner diameter of the rotor disks remains untreated.Alternatively, an outer layer initially formed on the inner diameter can be removed by local post-processing. For example, it is possible to treat the first and / or second rotor disk visible on the high-vacuum side, or alternatively or additionally, to treat all stator disks and / or all rotor disks visible on the high-vacuum side.

[0083] If rotor and / or stator disks visible on the high-vacuum side are left untreated, at least on their sides facing the high-vacuum environment, desorption processes can be avoided, thus enabling lower pressures. This also reduces heat radiation towards the recipient. Heating of sensitive devices connected to the turbomolecular pump on the high-vacuum side by thermal radiation can have detrimental effects, such as on measurement accuracy, and is therefore undesirable.

[0084] If rotor and / or stator disks visible on the high-vacuum side are at least partially treated on their sides facing the high-vacuum side, the advantage of improved heat dissipation from the rotor to the stator arises, which can compensate for or even overcompensate for the disadvantages of possible desorption processes or thermal radiation.

[0085] The compound of the metallic element is preferably a compound of a metallic element that constitutes a major component of the metallic material. This means that the compound of the metallic element is preferably a compound of a metallic element of which the metallic material consists to more than 10% by weight, more preferably to more than 25% by weight, even more preferably to more than 50% by weight, particularly preferably to more than 75% by weight, most preferably to more than 90% by weight, and most preferably to more than 95% by weight.

[0086] Because the metallic element contained in the compound formed by the oxidation treatment is identical to a major component of the metallic material, the outer layer represents an intimately bonded component of the workpiece, created by the transformation of the metal surface. This prevents the outer layer from detaching and ensures that it largely integrates into the base material.

[0087] The metallic material comprises a metallic element. The oxidation of this metallic element forms the metallic compound from which the outer layer on the treated surface is formed. The metallic element can preferably be aluminum, iron, copper, magnesium, nickel, or titanium.

[0088] The stator component comprises a metallic material. The metallic material is preferably aluminum, an aluminum alloy, iron, an iron alloy (for example, steel or cast iron), copper, a copper alloy, magnesium, a magnesium alloy, nickel or a nickel alloy, titanium or a titanium alloy.

[0089] An "alloy" is a single-phase or multi-phase metallic material consisting of a two- or multi-component system made up of two or more starting materials, where at least one of the starting materials is a metal. Alloy groups are named according to the element with the largest proportion; for example, an aluminum alloy is a metallic material in which aluminum, as the base metal, is the largest component, and one or more other alloying elements are present in smaller proportions.

[0090] The compound of the metallic element is preferably an oxygen compound or a sulfur compound of the metallic element, more preferably an oxygen compound of the metallic element. The sulfur compound may in particular be a sulfide or a sulfate. The oxygen compound is in particular an oxide, a hydroxide, and / or an oxide-hydroxide of the metallic element. The oxide, hydroxide, or oxide-hydroxide of the metallic element may also be in the form of a hydrate. Particularly preferably, the compound of the metallic element is an oxygen compound of aluminum, and most preferably an aluminum oxide, an aluminum hydroxide, and / or an aluminum oxide-hydroxide.

[0091] The outer layer formed by the oxidation treatment can essentially consist of a single compound of the metallic element (e.g., a single oxide), but it can also consist of several compounds of the metallic element, for example, an oxide and a hydroxide of the metallic element, or several different oxides of the metallic element. A metal can also be present in several oxidation states simultaneously in the outer layer, e.g., as iron(II) and iron(III), or as copper(I) and copper(II).

[0092] It is understood that the composition of the outer layer formed by oxidation treatment depends not only on the type of oxidizing agent and the process parameters of the oxidation treatment, but is also significantly determined by the composition of the metallic material. For example, oxidation treatment of an alloy of two or more metals can lead to the formation of an outer layer containing compounds of both metals. However, it is also possible that one of the alloying elements is relatively difficult to oxidize and is therefore present wholly or partially in an unoxidized form in the resulting outer layer. For example, anodizing an Al-Si alloy can lead to the formation of an anodized layer that, in addition to oxygen compounds of aluminum, also includes particles containing elemental silicon.Finally, it is also possible that one or more alloying elements are leached from the material surface during oxidation treatment. Therefore, the relative stoichiometric ratio of the alloying elements to each other in the outer layer may differ from the relative stoichiometric ratio of the alloying elements to each other in the untreated metallic material.

[0093] In any case, it is preferred that the main constituent by weight of the outer layer (e.g., at least 10, at least 25, at least 50, at least 75, at least 90, or at least 95 percent by weight) is formed by one or more compounds of the same metallic element that also forms the main constituent by weight of the metallic material. The proportion by weight of this metallic element in the metallic material and the proportion by weight of the compound(s) of this metallic element in the outer layer are preferably both at least 10 percent by weight, more preferably both at least 25 percent by weight, even more preferably both at least 50 percent by weight, particularly preferably both at least 75 percent by weight, most preferably both at least 90 percent by weight, and most preferably both at least 95 percent by weight.

[0094] As mentioned above, the outer layer formed during oxidation treatment grows largely into the metallic material. Therefore, relative to the untreated surface of the metallic material, it only partially contributes to the overall thickness. The total thickness of the resulting layer can be influenced by the choice of metallic material, the oxidation treatment process, and the process parameters (e.g., treatment duration). The layer thickness is preferably adjusted so that, relative to the untreated surface of the metallic material, the outer layer is 20 µm or less, preferably 10 µm or less, and more preferably 7 µm or less. This ensures dimensional accuracy relative to other components, even in areas with tight tolerances, such as a radial Holweck gap.

[0095] Preferably, the outer layer has a total thickness in the range of 15 µm to 30 µm, more preferably in the range of 20 µm to 25 µm.

[0096] In the present invention, the "total thickness" is understood to mean the sum of the thickness of the part of the outer layer that is applied to the untreated surface of the metallic material and the thickness of the part of the outer layer that has grown into the metallic material, relative to the untreated surface of the metallic material.

[0097] The invention is described below by way of example with reference to advantageous embodiments and the accompanying figures. These show, schematically: Fig. 1 a perspective view of a turbomolecular pump, Fig. 2 a view of the underside of the turbomolecular pump of Fig. 1 , Fig. 3 a cross-section of the turbomolecular pump along the in Fig. 2Section line AA shown, Fig. 4 a cross-sectional view of the turbomolecular pump along the in Fig. 2 Section line BB, Fig. 5 shows a cross-sectional view of the turbomolecular pump along the line shown in Fig. 2Fig. 6 shows a schematic cross-sectional view of a conventional, non-inventive turbomolecular pump according to the comparative example, Fig. 7 shows a schematic cross-sectional view of a turbomolecular pump according to the invention according to embodiment 1, Fig. 8 shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 2, Fig. 8A shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 2A, Fig. 9 shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 3, Fig. 10 shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 4, Fig. 10A shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 4A, Fig. 11 shows a schematic cross-sectional view of a turbomolecular pump according to embodiment 5.Fig. 12 a schematic cross-sectional view of a turbomolecular pump according to the invention according to embodiment 6, Fig. 13 a schematic cross-sectional view of a turbomolecular pump according to the invention according to embodiment 7, Fig. 14 a schematic cross-sectional view of a turbomolecular pump according to the invention according to embodiment 8, Fig. 15 a plot of the measured rotor temperature against the rotor speed in a turbomolecular pump according to the invention according to embodiment 4 and in the non-inventive turbomolecular pump according to the comparative example.

[0098] The in Fig. 1The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a receiver (not shown) can be connected in a manner known per se. The gas from the receiver can be drawn out of the receiver via the pump inlet 115 and conveyed through the pump to a pump outlet 117, to which a backing pump, such as a rotary vane pump, can be connected.

[0099] The inlet flange 113 forms a Fig. 1 The upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, to which an electronics housing 123 is attached laterally. The electronics housing 123 contains electrical and / or electronic components of the vacuum pump 111, e.g., for operating an electric motor 125 located in the vacuum pump (see also Fig. 3The electronics housing 123 has several connections 127 for accessories. In addition, a data interface 129, e.g. according to the RS485 standard, and a power supply connection 131 are located on the electronics housing 123.

[0100] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0101] The housing 119 of the turbomolecular pump 111 has a flood inlet 133, in particular in the form of a flood valve, through which the vacuum pump 111 can be flooded. In the area of ​​the lower part 121, a purge gas connection 135, also referred to as a purge gas connection, is also arranged, through which purge gas can be supplied to protect the electric motor 125 (see e.g. Fig. 3The gas pumped by the pump can be introduced into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111. Two coolant connections 139 are also arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant that can be directed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

[0102] The lower side 141 of the vacuum pump can serve as a base, allowing the vacuum pump 111 to be operated standing upright on its underside 141. Alternatively, the vacuum pump 111 can be attached to a receiver via the inlet flange 113 and thus operated in a suspended position. Furthermore, the vacuum pump 111 can be designed to operate even when oriented differently than described. Fig. 1 As shown. It is also possible to implement embodiments of the vacuum pump in which the underside 141 can be arranged facing sideways or upwards instead of downwards. In principle, any angle is possible.

[0103] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in a standing position.

[0104] On the underside 141, which is in Fig. 2As shown, various screws 143 are arranged, by means of which components of the vacuum pump, not further specified here, are fastened to one another. For example, a bearing cover 145 is attached to the underside 141.

[0105] Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached to a support surface, for example. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.

[0106] In the Figures 2 to 5 A coolant line 148 is shown, in which the coolant introduced and removed via the coolant connections 139 can circulate.

[0107] Like the sectional views of the Figures 3 to 5 As shown, the vacuum pump comprises several process gas pumping stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

[0108] A rotor 149 is arranged in the housing 119, which has a rotor shaft 153 rotatable about a rotation axis 151.

[0109] The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series to provide pumping action. These stages have several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119. Each rotor disk 155 and an adjacent stator disk 157 form a turbomolecular pump stage. The stator disks 157 are held at a desired axial distance from each other by spacer rings 159.

[0110] The vacuum pump also includes Holweck pump stages arranged radially within one another and connected in series to effectively pump the pump. Other turbomolecular vacuum pumps exist (not shown) that do not have Holweck pump stages.

[0111] The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the axis of rotation 151 and nested one inside the other in the radial direction. Furthermore, two cylindrical Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and nested one inside the other in the radial direction.

[0112] The pump-active surfaces of the Holweck pump stages are formed by the outer surfaces, i.e., the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 faces the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together they form the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together they form a second Holweck pump stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and together they form the third Holweck pumping stage.

[0113] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, through which the radially outer Holweck slot 171 is connected to the central Holweck slot 173. Furthermore, a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, through which the central Holweck slot 173 is connected to the radially inner Holweck slot 175. This connects the nested Holweck pump stages in series. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0114] The aforementioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have several Holweck grooves spiraling around the axis of rotation 151 in the axial direction, while the opposite outer surfaces of the Holweck rotor sleeves 163, 165 are smooth and drive the gas forward in the Holweck grooves for the operation of the vacuum pump 111.

[0115] For the rotatable mounting of the rotor shaft 153, a rolling bearing 181 is provided in the area of ​​the pump outlet 117 and a permanent magnet bearing 183 is provided in the area of ​​the pump inlet 115.

[0116] In the area of ​​the rolling bearing 181, a conical injection nut 185 with an outer diameter increasing towards the rolling bearing 181 is provided on the rotor shaft 153. The injection nut 185 is in sliding contact with at least one wiper of a fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), an injection screw may be provided instead of an injection nut. Since different designs are thus possible, the term "injection tip" is also used in this context.

[0117] The operating fluid reservoir comprises several stacked absorbent discs 187, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0118] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the fluid reservoir via the wiper to the rotating injection nut 185 and, as a result of centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 towards the rolling bearing 181, where it performs, for example, a lubricating function. The rolling bearing 181 and the fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

[0119] The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each containing a ring stack of several axially stacked permanent magnet rings 195, 197. The ring magnets 195, 197 face each other, forming a radial bearing gap 199, with the rotor-side ring magnets 195 arranged radially outside and the stator-side ring magnets 197 radially inside. The magnetic field present in the bearing gap 199 induces magnetic repulsion forces between the ring magnets 195, 197, which result in the radial support of the rotor shaft 153. The rotor-side ring magnets 195 are supported by a support section 201 of the rotor shaft 153, which radially surrounds the ring magnets 195 on the outside.The stator-side ring magnets 197 are supported by a stator-side support section 203, which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. Parallel to the axis of rotation 151, the rotor-side ring magnets 195 are fixed by a cover element 207 coupled to the support section 201. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction by a retaining ring 209 connected to the support section 203 and a retaining ring 211 also connected to the support section 203. A disc spring 213 may also be provided between the retaining ring 211 and the ring magnets 197.

[0120] Within the magnetic bearing, an emergency or catch bearing 215 is provided, which runs freely without contact during normal operation of the vacuum pump 111 and only engages when there is excessive radial deflection of the rotor 149 relative to the stator, in order to form a radial stop for the rotor 149 and thus prevent a collision between the rotor-side and stator-side structures. The catch bearing 215 is designed as an unlubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator, which causes the catch bearing 215 to be disengaged during normal pump operation. The radial deflection at which the catch bearing 215 engages is dimensioned to be large enough so that the catch bearing 215 does not engage during normal operation of the vacuum pump, and simultaneously small enough to prevent a collision between the rotor-side and stator-side structures under all circumstances.

[0121] The vacuum pump 111 comprises the electric motor 125 for rotating the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, whose rotor shaft 153 extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded in the section of the rotor shaft 153 extending through the motor stator 217. A space 219 is arranged between the motor stator 217 and the section of the rotor 149 extending through the motor stator 217. This space comprises a radial motor gap through which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

[0122] The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A purge gas, also known as a sealing gas, which can be, for example, air or nitrogen, can enter the motor compartment 137 via the purge gas connection 135. This purge gas protects the electric motor 125 from process gas, e.g., from corrosive components of the process gas. The motor compartment 137 can also be evacuated via the pump outlet 117, meaning that the vacuum pressure in the motor compartment 137 is at least approximately equal to that produced by the backing pump connected to the pump outlet 117.

[0123] Between the rotor hub 161 and a wall 221 bounding the engine compartment 137, a so-called labyrinth seal 223, which is known per se, can also be provided, in particular to achieve a better seal of the engine compartment 217 against the radially outside Holweck pump stages.

[0124] The turbomolecular pump described above is equipped with at least one stator component according to the invention, which interacts effectively with a rotor in a pumping stage and which has the features specified in the independent claims, namely in a Holweck stator of a Holweck pumping stage and / or in a stator disk of a turbomolecular pumping stage. Additionally, according to the first aspect of the invention, the turbomolecular pump described above is equipped with at least one rotor component according to the invention, which interacts effectively with a stator in a pumping stage and which has the features specified in independent claim 1, in particular in a rotor disk of a turbomolecular pumping stage, or in a rotor disk of a turbomolecular pumping stage.The turbomolecular pump described above, according to the second aspect of the invention, is equipped with at least one rotor component according to the invention, which interacts with a stator in a pumping stage and which has the features specified in independent claim 6. Advantageously, the turbomolecular pump can be equipped with several stator components and / or rotor components according to the invention, in particular several Holweck stators in Holweck pumping stages and / or several stator disks in turbomolecular pumping stages and / or several rotor disks in turbomolecular pumping stages.Particularly advantageous are a plurality of stator disks of the turbomolecular pump stages, in particular all stator disks of all turbomolecular pump stages designed according to the invention, and / or a plurality of rotor disks of the turbomolecular pump stages, in particular all rotor disks of all turbomolecular pump stages designed according to the invention, and at least the radially outer or all Holweck stators of all Holweck pump stages designed according to the invention are particularly advantageous.

[0125] Furthermore, it is advantageous if no turbomolecular pump stage of the turbomolecular pump described above includes a spacer ring with a treated surface.

[0126] The material of the untreated rotating components of the turbomolecular pump is not limited within the scope of the present invention. For example, rotor components can consist of a metallic material, a ceramic material and / or a composite material.

[0127] The rotor can be formed in one piece. It then consists of only a single rotor component and a single material, e.g., an aluminum alloy. In this case, the term "rotor component" used in the present invention refers to the entire rotor, and the rotor consists of a single rotor component.

[0128] However, it can be advantageous if the rotor is designed in multiple sections. In the present invention, a rotor designed in multiple sections is understood to be a rotor composed of at least two separate rotor components. For example, in a rotor designed in multiple sections, individual rotor disks may be mounted on a separately manufactured rotor shaft, and / or a Holweck rotor sleeve may be mounted on a separately manufactured Holweck hub.

[0129] A multi-component design offers the advantage that the individual rotor components can be made of different materials. For example, ceramic rotor disks can be mounted on a rotor shaft made of a metallic material, or a Holweck rotor sleeve made of a composite material can be attached to an aluminum Holweck hub. Furthermore, a multi-component rotor design also offers the advantage that, in a turbomolecular pump according to the first aspect of the invention, it is possible to freely select which rotor components undergo surface treatment and which remain untreated. Thus, for example, a rotor design can be implemented in which some rotor disks are treated while others remain untreated.

[0130] It goes without saying that a rotor component can only undergo oxidation treatment if it is made of an oxidizable metallic material. This is not possible with a rotor or rotor component made of ceramic or a composite material.

[0131] If a rotor component (or a one-piece rotor) is made of a metallic material, e.g. aluminum or an aluminum alloy, it (or he) may be free of an outer layer, i.e., not have been subjected to any oxidation treatment, or may have an outer layer produced by an oxidation treatment, or, in unclaimed embodiments, may have a nickel-containing coating.

[0132] The Figs. 6 to 14 show a comparison of schematic cross-sectional views of several differently designed turbomolecular pumps, including both turbomolecular pumping stages and Holweck pumping stages.

[0133] The housing 19, the rotor shafts 52 and the Holweck hubs 61 of the Holweck rotor, also called rotor hubs, arranged on the rotor shafts 52 rotating about an axis 51 during operation, exhibit in the turbomolecular pumps of Figs. 6 to 13 no outer layer, and can each be formed in the conventional manner, for example from an untreated aluminum alloy. The cylindrical Holweck rotor sleeves 63 attached to the Holweck hubs 61 also exhibit this in the turbomolecular pumps of Figs. 6 to 13 They have no outer layer and can each be formed in the conventional way, for example from a carbon fiber reinforced plastic (CFRP). However, they differ in the Figs. 6 to 13The radially nested, also cylindrical Holweck stator sleeves 67, 69 and 68, 70, which are also referred to simply as Holweck stators, differ from one another with regard to their surface finish. Furthermore, they differ in the Figs. 6 to 13 the stator disks 57, 58, the spacer rings 59, 60 and the rotor disks 54, 55 with regard to their surface finish.

[0134] The in Fig. 6 The system shown contains conventional Holweck stator sleeves 67, 69, which have no outer layer and no increased thermal emissivity. They can, for example, be made of a metallic material that has not been subjected to any oxidation treatment.

[0135] The in Fig. 8The system shown, however, contains Holweck stator sleeves 68, 70 according to the present invention, the dotted surfaces of which comprise an outer layer 80 produced by oxidation treatment with a compound of a metallic element contained in the metallic material. Therefore, they exhibit an increased thermal emissivity compared to conventional Holweck stators 67, 69 and thus result in improved heat dissipation. This applies in Fig. 8 both the radial inner and outer surfaces of the inner Holweck stator 70 and the radial inner surface of the outer Holweck stator 68, so that increased heat transfer by thermal radiation from the rotor to the stator occurs across the entire radial Holweck gap 71, 73. In the Fig. 8In the illustrated embodiment, each Holweck stator surface has, in its entirety, an outer layer 80 produced by oxidation treatment and thus an increased thermal emissivity. This includes not only the radial inner and outer surfaces, but also, as shown in Fig. 8 shown, the surfaces of the axially upper and lower ends, i.e. the end faces, of the Holweck stator sleeves 68, 70 with a.

[0136] It is understood that other embodiments are also possible within the scope of the invention, which differ from the one described in Fig. 8 The configuration of the Holweck system shown schematically may differ. For example, it is possible that not all stator surfaces shown in Fig. 8 are shown as dotted areas, but only a part of these areas has an outer layer 80 produced by an oxidation treatment.

[0137] In particular, it is possible, as in Fig. 10It has been shown that the radially inner Holweck stator sleeve 70 does not require any oxidation treatment. This can be advantageous because the presence of an outer layer 80 could be detrimental to the particularly high dimensional accuracy required to form a particularly narrow Holweck gap 73 between the rotor and stator. The oxidation treatment and the formation of the outer layer 80 can then be limited, in particular, to the surfaces of other stator components where the requirements for dimensional accuracy are lower, for example, the surfaces of the radially outer Holweck stator sleeve 68 and / or the surfaces of the stator disks 58.

[0138] In particular, it is also possible, as in Fig. 8A and Fig. 10A shown to leave the first stator disk 57, viewed from the high vacuum side, untreated, while all other stator disks 58 are treated.

[0139] The in the Figs. 6 to 14The turbomolecular pumps shown also comprise several turbomolecular pump stages connected in series, each consisting of a rotor disk 54, 55 attached to the rotor shaft 52 and a stator disk 57, 58 adjacent to it, wherein the stator disks 57, 58 are axially spaced apart from each other by spacer rings 59, 60.

[0140] The 59 spacer rings are in the Figs. 6 to 8 and the Figs. 10 to 14 They have not undergone any oxidation treatment, which is why they do not have an outer layer 80. They may, for example, consist of an untreated aluminum alloy.

[0141] As in Fig. 9As shown, it is generally possible to use spacer rings 60 that have undergone oxidation treatment and are provided with an outer layer 80. Surprisingly, however, it was found that spacer rings 60 treated in this way do not improve rotor cooling despite the resulting increased thermal emissivity of the spacer rings 60. It is therefore preferable to leave the spacer rings 59 untreated.

[0142] The untreated stator discs 57 in Fig. 6 , 7 , 8A , 10A and 13 differ from the treated stator disks 58 in the Figs. 8 to 14 .

[0143] The in Fig. 6The system shown, which is not according to the invention, contains conventional stator disks 57 that have no outer layer 80 and nowhere an increased thermal emissivity. They can, for example, consist of a metallic material that has not been subjected to any oxidation treatment.

[0144] Fig. 7 This also shows a system in which only stator disks 57 are present without an outer layer 80 and without increased emissivity. Unlike in Fig. 6 However, the Holweck stator sleeves 68, 70 here have an oxidation-treated surface with an outer layer 80. In the case of the Fig. 7 The configuration shown is therefore a system according to the invention.

[0145] The in Figs. 8 to 14The systems shown, however, contain stator disks 58 according to the present invention, the dotted surfaces of which comprise an outer layer 80 produced by oxidation treatment with a compound of a metallic element contained in the metallic material. Therefore, they exhibit a higher thermal emissivity compared to conventional stator disks 57 and thus result in improved heat dissipation. This applies in the Figs. 8 to 14 both the underside and the top side of the treated stator disks are affected, resulting in increased heat transfer by thermal radiation from the rotor to the stator across the entire axial gap 56. In the Figs. 8 to 14 In the embodiments shown, the surface of each treated stator disk 58 has, in its entirety, an outer layer 80 produced by oxidation treatment and thus an increased thermal emissivity. This implies, as shown in the Figs. 8 to 14 shown, in addition to the axially upper and lower surfaces, also the surfaces of the radially inner and outer ends of the treated stator disks 58.

[0146] It goes without saying that, deviating from the ones in the Figs. 8 to 14 In addition to the configurations shown, systems according to the invention (not shown in the figures) are also conceivable in which the surfaces of one or more stator disks 58 are not treated in their entirety, but only partially, e.g. only on a side facing away from the high vacuum side in the axial direction (lower side in the figures).

[0147] In the Fig. 8 , 9 , 10 , 11 , 12 and 14Embodiments are shown in which each stator disk 58 has a treated surface with an outer layer 80. However, it is also possible not to treat all stator disks of a turbomolecular pump according to the invention, but to leave one or more stator disks 57 untreated. Such a configuration is shown in the Fig. 8A , 10A and 13 shown. Here, the high-vacuum side (into the Fig. 8A , 10A , 13 (Viewed from above) the first stator disk 57 is untreated, while the second stator disk 58 is treated and visible from the high-vacuum side. The remaining stator disks 58 in the Fig. 8A , 10A and 13 are also treated.

[0148] In the Figs. 11 to 14Embodiments are shown in which, in addition to stator components, at least individual rotor components also have a treated surface with an outer layer 82 and increased emissivity. The embodiments shown in the Figs. 11 to 14 The outer layer 82 shown on the rotor components is formed by an oxidation treatment, as is the case with the stator components. In non-claimed embodiments, the outer layer 82 on the rotor components can also be formed from a nickel-containing material.

[0149] Fig. 11Figure 1 shows a turbomolecular pump in which, in addition to all stator disks 58 and all Holweck stator sleeves 68, 70, all rotor disks 55 are also treated. The rotor disks 55 are treated over their entire surface, with the exception of their inner diameters. Leaving the inner diameters of the rotor disks 55 untreated ensures a better fit of the rotor disks 55 to the rotor shaft 53, which is also untreated. The Holweck hub 61 and the Holweck rotor sleeves 63 are also untreated in this embodiment.

[0150] As in the Fig. 12 and 13As shown, embodiments are also possible in which some rotor disks 55 and / or stator disks 58 are treated, while other rotor disks 54 and / or stator disks 57 remain completely untreated. Preferably, at least one rotor disk and / or at least one stator disk visible from the high-vacuum side is treated. That is, for example, the second rotor disk and / or second stator disk can be treated and simultaneously be visible from the high-vacuum side (at least at a viewing angle deviating from the axial direction). In this case, all disks following the second stator disk and / or rotor disk are also treated.

[0151] Fig. 12 shows a turbomolecular pump with the same structure as in Fig. 11, except that, viewed from the high vacuum side, the first rotor disk 54 is untreated, while the first stator disk 58 is treated over its entire surface and is visible from the high vacuum side.

[0152] Fig. 13 shows a turbomolecular pump with the same structure as in Fig. 12 , except that, viewed from the high vacuum side, the first stator disk 57 is also untreated, while the second stator disk 58 is treated over its entire surface and is visible from the high vacuum side.

[0153] The in the Figs. 6 to 13 The rotors shown can have either a one-piece or a multi-piece construction.

[0154] Fig. 14In contrast, Figure 1 shows a rotor formed in one piece. It can be manufactured in one piece, for example from a metallic material, in particular from aluminum or an aluminum alloy. In the illustrated embodiment, the entire surface of the one-piece rotor has an outer layer 82, which is formed by an oxidation treatment or, in unclaimed embodiments, by coating with a nickel-containing material. Unlike in the embodiments of Figs. 11 to 13 The outer layer 82 is not limited to the rotor disks 55, but also covers the Holweck hub 62, the Holweck rotor sleeve 64, and the rotor shaft 53. Although in Fig. 14Not shown, the one-piece rotor can also be designed as a bell rotor, i.e., have an interior whose cross-section increases perpendicular to the axis of rotation in the axial direction starting from a high-vacuum side of the rotor arrangement, with the outer circumference of the rotor body also increasing in the same direction.

[0155] The layer thickness of the outer layer 80, 82 is in Figs. 7 to 14 For better illustration, the image is greatly exaggerated and not shown to scale.

[0156] The term "material" in Figs. 6 to 14 This should not be understood as a restriction to a single material, but also includes multiple materials within a rotor, stator, spacer ring, or housing. For example, the term "rotor material" should be understood to mean that the rotor shown may contain rotor components made of different materials.

[0157] The term "viewing direction from the high-vacuum side" in the schematic representation of Fig. 8A , 10A , 12 and 13 This should not be interpreted as a restriction to a purely axial viewing direction. The viewing angle from the high-vacuum side can deviate from the axial direction by more than 0° and less than 90°. Examples

[0158] In one embodiment, hereinafter referred to as Example 2, a turbomolecular pump according to the invention has a configuration as shown in Fig. 8 shown. All stator disks 58 and both Holweck stator sleeves 68, 70 are made of aluminium and have a blackened aluminium oxide layer 80 on their entire surface, which is formed by an anodizing process.

[0159] This anodizing process comprises a pretreatment (degreasing, pickling, and descaling), the actual anodizing (i.e., anodic oxidation), and a posttreatment (coloring and densification). For this purpose, each of the stator disks 58 and Holweck stator sleeves 68, 70, previously manufactured from aluminum using conventional methods, is first degreased and pickled in an alkaline bath. Subsequent descaling by immersion in a dilute acid solution removes adhering residues of the alkaline solution as well as the existing natural oxide layer (formed by reaction with atmospheric oxygen) on the aluminum surface. After these pretreatment steps, the actual anodizing (anodic oxidation) of the stator component is carried out to a target thickness of the total outer layer of 20 to 25 µm. At a total outer layer thickness of 20 µm, the outer layer adds 7 µm to the untreated aluminum surface.The anodized stator component, with its aluminum oxide layer on the surface, is then immersed in a solution of an organic dye. The resulting porous aluminum oxide layer turns black as the dye is incorporated into the pores. Finally, the dyed stator component is immersed in boiling water, causing the aluminum oxide to expand and thus sealing the pores.

[0160] The outer layer 80 thus formed covers substantially the entire surface of each stator disk 58 and both Holweck stator sleeves 68, 70. Only the contact points necessary for carrying out the above anodizing process (e.g., for establishing the electrical contact during anodic oxidation) are not covered by the outer layer 80. When the present invention refers to the "entire" surface or the "totality" of the surface, this also includes a portion of the surface that is less than 100% for technical reasons. No post-processing is carried out in which parts of the outer layer are removed.

[0161] In contrast, the spacer rings 59, which are also made of aluminium, are not anodized in example 2 and therefore do not have an outer layer 80.

[0162] Likewise, the housing 19, the rotor shaft 52, the rotor disks 54, and the Holweck hub 61 are made of aluminum, which is not anodized and therefore has no outer layer 80. The rotor is of multi-part construction, with a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and thus also lacks an outer layer 82). This applies to Example 2 described here, as well as to Examples 1, 2A, 3, 4, and 4A explained below, and to the comparative example.

[0163] In a further embodiment, hereinafter referred to as Example 2A, a turbomolecular pump according to the invention has the same structure as described above for Example 2, except that the first stator disk 57, viewed from the high-vacuum side, is untreated and has no outer layer 80. The configuration of the turbomolecular pump according to Example 2A is described in Fig. 8Ashown, with the high vacuum side located at the top of the pump shown.

[0164] In a further embodiment, hereinafter referred to as Example 1, a turbomolecular pump according to the invention has the same structure as described above for Example 2, except that all stator disks 57 are untreated and do not have an outer layer 80. That is, in Example 1, although both Holweck stator sleeves 68, 70 have a blackened aluminum oxide layer 80 on their entire surface, formed by the anodizing process described above, none of the stator disks 57 are anodized. The configuration of the turbomolecular pump according to Example 1 is in Fig. 7 depicted.

[0165] In a further embodiment, hereinafter referred to as Example 3, a turbomolecular pump according to the invention has the same structure as described above for Example 2, except that, in addition to the entire surface of all stator disks 58 and the entire surface of both Holweck stator sleeves 68, 70, the entire surface of the spacer rings 59 is also anodized and blackened according to the method described above. The configuration of the turbomolecular pump according to Example 3 is in Fig. 9 depicted.

[0166] In a further embodiment, hereinafter referred to as Example 4, a turbomolecular pump according to the invention has the same structure as described above for Example 2, except that of the two Holweck stator sleeves, only the radially outer Holweck stator sleeve 68 has a blackened aluminum oxide layer 80, which is formed by the anodizing process described above. That is, in Example 4, the entire surfaces of all stator disks 58 and the entire surface of the radially outer Holweck stator sleeve 68 are anodized and blackened according to the above process, while the radially inner Holweck stator sleeve 69 remains untreated and thus has no outer layer 80. The configuration of the turbomolecular pump according to Example 4 is shown in Fig. 10 depicted.

[0167] In a further embodiment, hereinafter referred to as Example 4A, a turbomolecular pump according to the invention has the same structure as described above for Example 4, except that the first stator disk 57, viewed from the high-vacuum side, is untreated and has no outer layer 80. The configuration of the turbomolecular pump according to Example 4A is described in Fig. 10A shown, with the high vacuum side located at the top of the pump shown.

[0168] In a further embodiment, hereinafter referred to as Example 5, a turbomolecular pump according to the invention has the same structure as described above for Example 2, except that all rotor disks 55 additionally have an aluminum oxide layer 82 formed by anodic oxidation. This is an electrolytic process in which an external current source is used, and the rotor disk to be treated is connected as the anode, so that the surface of the aluminum material is converted into aluminum oxide. For this purpose, the rotor disk is immersed in an aqueous salt solution serving as the electrolyte. Through the action of an oxygen plasma generated in the electrolyte on the metal surface, a porous but firmly adhering oxide layer is formed on the treated component, which is not colored in the present embodiments 5 to 8, but can optionally be colored, in particular blackened.The oxide layer thus produced grows, due to its increase in volume, 50% of its thickness into the base material and 50% outwards. Subsequently, the rotor disk 55, treated by the above oxidation process, is post-treated by immersion in PTFE.

[0169] This means that in Example 5, not only are the entire surfaces of all stator disks 58 and the entire surfaces of both Holweck stator sleeves 68, 70 oxidized, but also the surfaces of all rotor disks 55, with the inner diameter of the rotor disks 55 remaining untreated. Alternatively, an outer layer initially formed on the inner diameter can be removed by local post-processing. The rotor shaft 52 and the Holweck hub 61 remain completely untreated and thus have no outer layer 82. The rotor is multi-part, with a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and thus also has no outer layer 82). The configuration of the turbomolecular pump according to Example 5 is shown in Fig. 11 depicted.

[0170] In a further embodiment, hereinafter referred to as Example 6, a turbomolecular pump according to the invention has the same structure as described above for Example 5, except that the first rotor disk 54, viewed from the high-vacuum side, remains untreated. That is, in Example 6, the entire surfaces of all stator disks 58 and the entire surfaces of both Holweck stator sleeves 68, 70 are coated with a blackened aluminum oxide layer 80 formed by the anodizing process described in Example 2, and additionally, the surfaces of all rotor disks 55, except for the first rotor disk 54 viewed from the high-vacuum side, are treated by the anodic oxidation process described in Example 5 and post-treated with PTFE, wherein the respective inner diameter of the rotor disks 55 has no outer layer.The absence of the outer layer 82 on the inner diameter of the rotor disks 55 can result either from leaving the inner diameter untreated from the outset, or from removing an outer layer 82 initially formed during the treatment of the rotor disk 55 by local post-processing of the inner diameter. The rotor shaft 52 and the Holweck hub 61 remain completely untreated and therefore have no outer layer 82. The rotor is multi-part, with a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and thus also lacks an outer layer 82). The first stator disk 58, viewed from the high-vacuum side, is anodized and visible from the high-vacuum side. The configuration of the turbomolecular pump according to Example 6 is shown in [reference missing]. Fig. 12 shown, with the high vacuum side located at the top of the pump shown.

[0171] In a further embodiment, hereinafter referred to as Example 7, a turbomolecular pump according to the invention has the same structure as described above for Example 6, except that the first stator disk 57, viewed from the high-vacuum side, also remains untreated. That is, in Example 7, the entire surfaces of both Holweck stator sleeves 68, 70, and additionally the entire surfaces of all stator disks 58 and the surfaces of all rotor disks 55, except for the first rotor disk 54 and first stator disk 57 viewed from the high-vacuum side, are coated with an aluminum oxide layer 80, 82 formed by the oxidation process described in Example 2 (for stator components) and Example 5 (for rotor disks), respectively, wherein the respective inner diameter of the rotor disks 55 has no outer layer 82 and the rotor disks 55 are further treated by immersion in PTFE.The absence of the outer layer 82 on the inner diameter of the rotor disks 55 can result either from leaving the inner diameter untreated from the outset, or from removing an outer layer 82 initially formed during the treatment of the rotor disk 55 by local post-processing of the inner diameter. The rotor shaft 52 and the Holweck hub 61 remain completely untreated and therefore have no outer layer 82. The rotor is of a multi-part construction, with a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and thus also lacking an outer layer 82). The second stator disk 58, viewed from the high-vacuum side, is anodized and blackened and is visible from the high-vacuum side. The configuration of the turbomolecular pump according to Example 7 is shown in [reference missing]. Fig. 13 shown, with the high vacuum side located at the top of the pump shown.

[0172] In a further embodiment, hereinafter referred to as Example 8, a turbomolecular pump according to the invention has a structure as described in Fig. 14As in Example 5, in Example 8 the entire surfaces of both Holweck stator sleeves 68, 70 and the entire surfaces of all stator disks 58 are coated with a blackened aluminum oxide layer 80 formed by the anodizing process described above. However, unlike in Example 5, in Example 8 the rotor is formed in one piece from aluminum and coated on its entire surface with an aluminum oxide layer 82, which is produced by the oxidation process described in Example 5 and post-treated with PTFE. That is, in Example 8 the entire rotor consists of aluminum, and all accessible surfaces of the rotor shaft 53, all rotor disks 55, the Holweck hub 62, and the Holweck rotor sleeve 64 are coated with an aluminum oxide layer 82. The configuration of the turbomolecular pump according to Example 8 is shown in Fig. 14 depicted.

[0173] In unclaimed embodiments, the outer layer 82 applied to the rotor disks 55 or the entire one-piece rotor in Examples 5 to 8 can alternatively be formed by coating with a nickel-containing material. It is understood that the outer layer 82 applied to the rotor disks 55 or the entire one-piece rotor in Examples 5 to 8 can alternatively also be formed by anodizing, for example, by the anodizing process described above in Example 2. That is, both the treated stator components and the treated rotor components can be anodized, and the stator and rotor components can be treated using the same anodizing process.

[0174] In a comparative example, a non-inventive turbomolecular pump possesses the in Fig. 6The assembly shown is as follows. That is, neither the Holweck stator sleeves 67, 69 nor the stator disks 57 are anodized. They therefore consist of untreated aluminum without an outer layer 80. The same applies to the spacer rings 59, the housing 19, the rotor shaft 53, the rotor disks 54, and the Holweck hub 61. As in Examples 1 to 7, the rotor is constructed in multiple parts, with the Holweck rotor sleeve 63 being made of carbon fiber reinforced plastic (CFRP) (and thus also lacking an outer layer 82).

[0175] The effects of different surface treatments on heat dissipation were experimentally verified for turbomolecular pumps according to the comparative example and according to embodiments 1 to 4. All turbomolecular pumps in the aforementioned examples were identically dimensioned and differed only in which stator components had a blackened anodized layer 80. To determine the effectiveness of the heat dissipation, the same quantity of the same gas was pumped with each of the aforementioned turbomolecular pumps, with the rotational speed gradually increased and the rotor temperature measured as a function of the rotor speed using an infrared thermometer. The results of these experiments are summarized in Table 1. Table 1: Temperature change of the rotor depending on the configuration Example Anodized blackened components * Δ Rotor temperature in [°C] Comparative example None (as in Fig. 6 shown) - Example 1 Both Holweck stator sleeves 68, 70 (as in Fig. 7 shown) -1 Example 2 Both Holweck stator sleeves 68, 70 + all stator disks 58 (as in Fig. 8 shown) -11 Example 3 Both hollow stator sleeves 68, 70 + all stator disks 58 + all spacer rings 59 (as in Fig. 9 shown) -6 Example 4 Radial outer hollow stator 68 + all stator disks 58 (as in Fig. 10 shown) -7 * All components not explicitly listed as "anodized blackened components" in the respective example are untreated, i.e., not anodized.

[0176] In all examples according to the invention, i.e., when using anodized and blackened stator components, a reduction in rotor temperature is observed compared to the temperature measured under otherwise identical test conditions in the comparative example, i.e., on the rotor of a conventional turbomolecular pump, which contains only untreated but otherwise identical stator components.

[0177] A particularly significant reduction in rotor temperature, namely by -11°C, can be observed in Example 2 when the radially outer Holweck stator sleeve 68, the radially inner Holweck stator sleeve 70, and all stator disks 58 are anodized and blackened across their entire surface. Surprisingly, however, the additional anodizing and blackening of the spacer rings 60, as shown in Example 3, does not lead to an even greater effect, but rather to a smaller reduction of only -6°C compared to the rotor temperature of the comparison example. The smaller reduction in rotor temperature can be explained by the fact that the coated spacer rings 60, while having a higher emissivity, simultaneously exhibit poorer heat transfer to the housing than the untreated spacer rings 59.

[0178] In Example 1, the two Holweck stator sleeves 68, 70, but none of the stator disks 57, are anodized and blackened. While there is a reduction in rotor temperature compared to the reference example, this reduction is only -1°C, and therefore significantly less than in Example 2, where the otherwise identical turbomolecular pump additionally contains anodized and blackened stator disks 58.

[0179] In Example 4, all stator disks 58 and the radially outer Holweck stator sleeve 68 are anodized and blackened over their entire surface, while the radially inner Holweck stator sleeve 69 remains untreated. This results in a significant reduction in rotor temperature of -7°C compared to the comparison example. A plot of the measured rotor temperatures (y-axis) against the rotational speed (x-axis) for the turbomolecular pump according to the comparison example (dashed line) and according to embodiment 4 (solid line) is shown in Fig. 15 This graph shows that the difference in rotor temperature exists across the entire investigated speed range and increases towards higher speeds.

[0180] Surprisingly, the examples above show that in a turbomolecular pump according to the invention, significantly improved heat dissipation can be achieved compared to an otherwise identical turbomolecular pump with untreated stator components, even though the treated stator components used were treated on their entire surface without any subsequent removal of the outer layer at contact, fitting or dimension surfaces. Reference symbol list

[0181] 19 Housing 51 Rotation axis 52 Rotor shaft 53 Rotor shaft 54 ​​Rotor disk 55 Rotor disk 56 Axial gap 57 Stator disk 58 Stator disk 59 Spacer ring 60 Spacer ring 61 Holweck hub, rotor hub 62 Holweck hub, rotor hub 63 Holweck rotor sleeve 64 Holweck rotor sleeve 67 Outer Holweck stator sleeve 68 Outer Holweck stator sleeve 69 Inner Holweck stator sleeve 70 Inner Holweck stator sleeve 71 Holweck gap 73 Holweck gap 80 Outer layer 82 Outer layer 111 Turbomolecular pump 113 Inlet flange 115 Pump inlet 117 Pump outlet 119 Housing 121 Lower part 123 Electronics housing 125 Electric motor 127 Accessory connection 129 Data interface 131 Power supply connection 133 Flood inlet 135 Sealing gas connection 137 Engine compartment 139 Coolant connection 141 Underside 143 Screw 145 Bearing cover 147 Mounting hole 148 Coolant line 149 Rotor 151 Rotation shaft 153 Rotor shaft 155 Rotor disc 157 Stator disc 159 Spacer ring 161 Rotor hub 163 Holweck rotor sleeve 165 Holweck rotor sleeve 167 Holweck stator sleeve 169 Holweck stator sleeve171 Holweck gap 173 Holweck gap 175 Holweck gap 179 Connecting channel 181 Rolling bearing 183 Permanent magnet bearing 185 Injection nut 187 Washer 189 Insert 191 Rotor-side bearing half 193 Stator-side bearing half 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Support section 203 Support section 205 Radial strut 207 Cover element 209 Support ring 211 Mounting ring 213 Disc spring 215 Emergency or catch bearing 217 Motor stator 219 Gap 221 Wall 223 Labyrinth seal

Claims

1. A turbomolecular pump (111) comprising a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises a stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and which cooperates with the stator in a pump-active manner, wherein the stator has at least one stator component (58, 68, 70, 157, 167, 169) comprising a stator component surface and the entirety of the stator component surface is treated by oxidation, and the rotor (149) has at least one rotor component (53, 55, 153, 155) comprising a rotor component surface and a portion of the rotor component surface or the entirety of the rotor component surface is treated by oxidation, wherein the treated stator component (58, 68, 70, 157, 167, 169) and the treated rotor component (53, 55, 153, 155) comprise a metallic material which contains at least one metallic element, wherein the treated entirety of the stator component surface comprises an outer layer (80) which comprises a compound of the metallic element produced by the oxidation treatment, and wherein the treated portion of the rotor component surface or the treated entirety of the rotor component surface comprises an outer layer (82) which comprises a compound of the metallic element produced by the oxidation treatment, wherein the treated stator component (58, 68, 70, 157, 167, 169) is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage of the turbomolecular pump (111) and / or a stator disk (58, 157) of a turbomolecular pump stage of the turbomolecular pump (111), and wherein the turbomolecular pump stage comprises spacer rings (59, 159) for the stator disks (57, 58, 157), and wherein none of the spacer rings (59, 159) has a surface treated by oxidation.

2. A turbomolecular pump (111) according to claim 1, wherein the treated rotor component is a rotor disk (55, 155) of a turbomolecular pump stage of the turbomolecular pump (111).

3. A turbomolecular pump (111) according to claim 1 or 2, wherein the turbomolecular pump stage has a plurality of rotor disks (54, 55, 155), wherein a plurality of rotor disks (55, 155) or all the rotor disks (55, 155) of the turbomolecular pump stage are treated.

4. A turbomolecular pump (111) according to any one of the preceding claims, wherein the turbomolecular pump (111) comprises at least one turbomolecular pump stage having a plurality of rotor disks (54, 55, 155), and wherein, in the or each turbomolecular pump stage, either all the rotor disks (55, 155) are treated or a plurality of rotor disks (55, 155) are treated and one or more rotor disks (54, 155) are untreated.

5. A turbomolecular pump (111) according to any one of the claims 2 to 4, wherein at least one rotor disk (55, 155) of the turbomolecular pump stage, which is visible from a high vacuum side of the turbomolecular pump (111), is treated.

6. A turbomolecular pump (111) comprising a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises a stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and which cooperates with the stator in a pump-active manner, wherein the stator has at least one stator component (58, 68, 70, 157, 167, 169) having a stator component surface and the entirety of the stator component surface is treated by oxidation, and the rotor (149) has at least one rotor component (52, 54, 153, 155) having a rotor component surface and the entirety of the surfaces of all the rotor components (52, 54, 153, 155) is completely untreated, i.e. is neither treated by oxidation nor coated in any other way, wherein the treated stator component (58, 68, 70, 157, 167, 169) comprises a metallic material which contains at least one metallic element, wherein the treated entirety of the stator component surface comprises an outer layer (80) which comprises a compound of the metallic element produced by the oxidation treatment, wherein the treated stator component (58, 68, 70, 157, 167, 169) is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage of the turbomolecular pump (111) and / or a stator disk (58, 157) of a turbomolecular pump stage of the turbomolecular pump (111), and wherein the turbomolecular pump stage comprises spacer rings (59, 159) for the stator disks (57, 58, 157), and wherein none of the spacer rings (59, 159) has a surface treated by oxidation.

7. A turbomolecular pump (111) according to any one of the preceding claims, wherein the turbomolecular pump stage has a plurality of stator disks (57, 58, 157), wherein a plurality of stator disks (58, 157) or all the stator disks (58, 157) of the turbomolecular pump stage are treated.

8. A turbomolecular pump (111) according to any one of the preceding claims, wherein the Holweck pump stage comprises a radially outer Holweck stator (68, 167) and one or more radially inner Holweck stators (69, 70, 169), of which either all the Holweck stators (68, 70, 167, 169) are treated or only the radially outer Holweck stator (68, 167) is treated.

9. A turbomolecular pump (111) according to any one of the preceding claims, wherein the turbomolecular pump (111) comprises at least one turbomolecular pump stage having a plurality of stator disks (57, 58, 157) and at least one Holweck pump stage having a radially outer Holweck stator (68, 167) and one or more radially inner Holweck stators (69, 70, 169), and wherein, in the or each turbomolecular pump stage, either all the stator disks (58, 157) are treated or a plurality of stator disks (58, 157) are treated and one or more stator disks (57, 157) are untreated, and wherein, in the or each Holweck pump stage, of the Holweck stators (68, 69, 70, 167, 169), either all the Holweck stators (68, 70, 167, 169) are treated or only the radially outer Holweck stator (68, 167) is treated.

10. A turbomolecular pump (111) according to any one of the preceding claims, wherein at least one stator disk (58, 157) of the turbomolecular pump stage, which is visible from a high vacuum side of the vacuum pump (111), is treated.

11. A turbomolecular pump (111) according to any one of the preceding claims, wherein the metallic element is aluminium, iron, copper, magnesium, nickel or titanium and / or the metallic material is aluminium, an aluminium alloy, iron, an iron alloy, copper, a copper alloy, magnesium, a magnesium alloy, nickel or a nickel alloy, titanium or a titanium alloy.

12. A turbomolecular pump (111) according to any one of the preceding claims, wherein the compound of the metallic element is an oxygen compound or a sulphur compound of the metallic element.

13. A turbomolecular pump (111) according to any one of the preceding claims, wherein, with respect to the untreated surface of the metallic material, the outer layer (80, 82) is applied up to a thickness of 20 µm or less, preferably 10 µm or less, more preferably 7 µm or less.

14. A turbomolecular pump (111) according to any one of the preceding claims, wherein the outer layer (80, 82) produced by the oxidation treatment has a total thickness in the range of 15 µm to 30 µm, preferably in the range of 20 µm to 25 µm.

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